Lorenzo von Fersen

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A bottlenose dolphin was trained to discriminate two simultaneously presented stimuli differing in numerosity (defined by the number of constituent elements). After responding correctly to stimuli consisting of three-dimensional objects, the dolphin transferred to two-dimensional stimuli. Initially, a variety of stimulus parameters covaried with the(More)
Eight pigeons were trained to discriminate between sets of color photographs of natural scenes. The scenes differed along five two-valued dimensions (site, weather, camera distance, camera orientation, and camera height), and all combinations of the feature values were used. One value of each dimension was designated as positive, and slides containing three(More)
The aim of the present study was to investigate whether bottlenose dolphins have cerebral asymmetries of visual processing. The monocular performance of the adult dolphin Goliath was tested using a large number of simultaneous multiple pattern discrimination tasks. The experiments revealed a clear right eye advantage in the acquisition and the retention of(More)
A previous behavioural study with a single bottlenose dolphin had reported a right eye superiority in visual discrimination tasks, indicating a left hemisphere dominance for visual object processing. The presence of a functional asymmetry demonstrated with one individual shows that this function can be lateralized in this single animal, but cannot reveal if(More)
Two adult female bottlenose dolphins were tested for cerebral asymmetries in the visuospatial domain. The animals learned under binocular conditions a three-choice spatial discrimination task with three hoops positioned along a line in the middle of the tank. During a correct trial the dolphins had to swim from a starting position at the tanks wall through(More)
In a two-choice discrimination paradigm, a bottlenose dolphin discriminated relational dimensions between visual numerosity stimuli under monocular viewing conditions. After prior binocular acquisition of the task, two monocular test series with different number stimuli were conducted. In accordance with recent studies on visual lateralization in the(More)
Pigeons were conditioned with a symbolic matching-to-sample paradigm. Six visual patterns in 16 configurations were presented in an operant chamber where reinforcement was delivered next to the correct keys. A test with novel configurations, planned to demonstrate associative transitivity between equivalent stimuli, revealed instead a different but(More)
A previous study (Kilian et al., 2003) had demonstrated that bottlenose dolphins can discriminate visual stimuli differing in numerosity. The aim of the present study was twofold: first, we sought to determine if dolphins are able to use a numerical category based on "few" vs. "many" when discriminating stimuli according to the number of their constituent(More)
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